DRCOG presents draft High‑Injury Network and four options for a smaller "critical corridors" prioritization

Denver Regional Council of Governments (DRCOG) staff presented a draft update to the region’s High‑Injury Network (HIN) and proposed four methods for creating a smaller “critical corridors” list to concentrate safety investments.

The session opened with DRCOG staff explaining the HIN’s purpose: “it identifies the roads with the highest concentrations of fatal and serious injury crashes,” and noted the draft uses a slightly different crash dataset that includes minor pedestrian and bicycle injuries to better align with local methodologies. Staff said the draft and the 2020 network cover roughly the same share of regional road miles (about 9%), and reported the draft captures slightly more KSI crashes (about 77% in the draft versus 75% in the 2020 network).

DRCOG described a methodological change lowering the corridor selection threshold from 3 crashes per mile to 2 crashes per mile to add routes — particularly in rural areas — and to better serve jurisdictions that lack their own local safety plan. “The intent was basically just to allow more routes to be on the HIN, particularly in rural areas that might otherwise be excluded,” a staff presenter said.

Staff illustrated coding and capture limits with local examples. In Broomfield, Miramonte Boulevard’s crashes concentrated at an intersection, leading to differing corridor assignments that local staff asked be reconsidered. In Jefferson County, Pleasant Park Road had five widely spaced motorcycle crashes that an automated coding step initially missed; DRCOG said manual review would restore corridors that meet the threshold when combined.

Participants raised technical and policy questions. Littleton asked whether DRCOG’s sliding‑window GIS approach is replicable by smaller agencies; DRCOG staff and a JIS specialist said the method is largely automatable but depends on input data (DRCOG used CDOT’s linear referencing), so exact replication may require manual adjustments. DRCOG offered one‑on‑one support for local replication needs.

The meeting then focused on critical corridors — a proposed second level of prioritization intended to spotlight a far smaller share of roadway miles that account for a disproportionate share of KSI crashes. DRCOG framed four options: • Option 1, a regional approach, selects the top 20% of routes by crashes per mile and raw crash counts (most focused on regionwide KSI reduction but risks leaving some counties without critical corridors). • Option 2, equal county, assigns the top 10 routes per county (urban routes ≥1 mile; rural ≥0.5 mile) to guarantee county representation. • Option 3 apportions corridors by each county’s share of the region’s KSI crashes (a data‑driven balance with minimum distribution). • Option 4 mirrors the RTP project allotment method (population, employment, VMT) to allocate corridors, increasing county distribution but potentially under‑emphasizing crash impact.

Tom Walker (City of Aurora, senior transportation planner) cautioned against Option 4: “Really concerned about option 4, simply because that doesn't seem to address the underlying focus of this group, which is looking at the best options for addressing crashes on a regional effort.” Multiple attendees pressed whether any chosen approach would be used in TIP funding decisions; DRCOG said the TIP policy is still under review and that critical corridors would likely be supplemental to—not a replacement for—the HIN, but acknowledged funding ties would shape preferences.

Rural representatives repeatedly urged alternatives or supplemental analyses for low‑crash but high‑severity contexts. Emily (City of Littleton) and Jefferson County staff suggested tiered or context‑sensitive analyses (urban/suburban/rural) or a separate systemic high‑risk analysis to better reflect rural corridor characteristics.

DRCOG asked members to complete a short survey by the following Friday indicating a preferred option or proposing hybrids; staff said they would provide HIN GIS products with crash metrics (KSI per mile, percentiles) so local agencies can perform their own rankings.

The group did not take a formal vote. The next DRCOG Vision 0/HIN working group meeting was announced for June 9 (virtual).